Combustion control



Jan. 14, 1947. H. MALONE ETAL 2,414,112

COMBUSTION CONTROL Filed June 23 1941 j INVENTORS HUMER E. MALDNE AND ELIFFURD HUTEHI/{IEE BY m ATTORNEK 5 I I I i F I I i I a I I I r v v a 1 5 4 fire device which is indicated as a timer 22, this timer having a synchronous motor 3 which is connected across line wires l6 and I1, driving a cam 24 which operates a switching mechanism 25 connected in parallel with thermostat l8. This timer serves to operate the stoker independently of the thermostat for short periods which are suificient to maintain the fire alive during mild weather when the thermostat remains satisfied for long periods of time.

The stoker I also includes an air control device generally indicated as 28, the details of which are shown in Fig. 2. Referring to this figure, an air d amper 23 is located within the air duct 5 and is fixed to a pivotally mounted shaft which extends through the side of the duct, this shaft being secured to a disc 3| which forms a part of a motion transmitting means. The shaft 36 also includes a ratchet wheel 32 which is free to rotate with respect to the shaft. The disc 3| carries a pair of pawls 33 and 34, which pawls have faces 35 and 36 which are adapted to engage the teeth on the ratchet wheel 32. The paw-s 33 and 34 are carried by pivot pins 31 and 38 which are secured to the disc 3|. The pawls 33 and 34 also include extension portions 39 and 40 between which extends a compression spring 4| This spring urges both pawls toward engagement with the teeth on ratchet wheel 32. The pawls 33 and 34 extend beyond the edge of disc 3|, the pawl 33 being adapted to engage a fixed stop member 42 which may be secured to the air duct 5, and the pawl 34 being adapted to engage an adjustable stop member 43. This stop member 43 may be carried by a plate 44, this plate being pivoted to the shaft 36 and having an arcuate slot 45 therein for receiving a set screw 46 WillCh screws into the air duct 5. This arrangement permits adjustment of the stop member 43 to any desired position, the screw 46 then being tightened for looking it in such position. If desired the duct 5 and the plate 44 may carry suitable indicia 41 for indicating the position to which the damper is adjusted to open.

The ratchet Wheel 32 is rotated by means of a thermal damper operator generally indicated as 56. This operator may consist of a base 5| which is mounted on the duct 5 and which is provided with out-turned portions 52 and 53 which form the side walls of a housing. A suitable cover for the housing may be screwed thereto by means of screws 54. Located within the housing is a thermostatic actuator or operating unit generally indicated as 56. This unit may include a first bimetal element 51 which is attached to the wall portion 53 by means of a bracket 58. The other end of element 51 is attached to a spacer 59 which in turn is attached to a second bimetal element 60. The elements 51 and 60 are turned oppositely so that the position of the free end of element 66 is determined by the cumulative effect of both elements. The free end of element 60 is attached to a cantilever portion 6| which is attached by a link 62 to a pin 63 secured to the ratchet wheel 32. The operating unit 56 also includes a center tapped electric heater 64. When this electric heating means is energized the elements 51 and 60 warp for causing upward movement of the cantilever portion 6|, which through the link 62 causes clockwise rotation of the ratchet wheel 32. When the electric heater 64 is deenergized the bimetal elements cool and return to the position shown, thus causing counterclockwise rotation of the ratchet wheel 32. Preferably, the electric heater 64 is secured at its mid-portion to element 51 by a rivet 65'. This heater may also be backed by a copper strip 65 which is also secured to the element 51 by a rivet 65', the ends of this strip extending through holes in element 51 and being bent inwardly as shown. This serves to conduct heat from the heater to element 51 even when this element is flexed, for permitting quick heating of this element.

The base 5| may also carry a terminal board 66 which is secured to the side walls 52 and 53 by brackets 61. This terminal board 66 carries terminals 68 and 69. It also may carry a portion of a switching mechanism for the heater 64. This switching mechanism may consist of a pair of spring contact blades 16 and 1| which are carried by a screw 12, these blades being spaced apart by an insulating spacer 13, and being spaced from the panel 66 by a spacer 14. A rigid blade 15 is preferably located adjacent the spring blade 16 for limiting upward movement of this blade. The blade 1| is adapted to be pressed into engagement with the blade 10 by means of an operating member 16 which is secured to the cantilever portion 6|. The position of the free end of element 16 may be adjusted by means of an adjusting screw 11. When the thermostatic element formed of bimetal elements 51 and 60 is cold, the parts assume the position shown in which the contact blade 1| is pressed into engagement with contact blade 16, this blade at this time being pressed away from its stop 15. As the thermostatic element heats up, the cantilever portion 6| rises and the switch operating member 16 rises correspondingly. During this movement the contact blades 10 and 1| move upwardly together and remain engaged. However, upon continued movement the blade 16 engages its stop 15 so that upon slightly further movement of the bimetal element the contact blade 1| disengages the contact blade 16. It will be noted that the terminal 68 is connected by a wire to wire 20 (in Fig. 1) and the terminal 69 is connected by wire 8| to the ground wire 2|. This ground terminal 69 is attached by a lead 82 to the center of heater 64. The terminal 68 is attached directly to one portion of the heater 64 by a lead 83 and is also attached by a lead 84 to the spring blade 1|, the cooperating spring blade 10 being attached by a lead 85 to the other end of heater 64.

Operation With the parts in the positions shown, the room thermostat I8 is satisfied and the relay 8 is deenergized, thus deenergizing the stoker m0- tor 6 and also the electric heater 64 of the damper operator. The thermostatic element of the damper operator is also cool which causes the cantilever portion 6| to assume the position shown in which the damper 29 is in closed position. At this time the contact blade 1| is pressed into engagement with contact blade 10 and thus both portions of the heater 64 are connected in parallel with the stoker motor 6. When the room thermostat l8 calls for heat, the relay 8 is energized which in turn energizes the stoker motor 6 and both portions of the heater 64. The stoker therefore feeds coal to the retort 2, increasing the thickness of the fuel bed and at the same time agitating the coal in the bed so that any free ash may be shaken down into the bed. With both sections of the heater 64 energized, the thermostatic actuator becomes heated relatively rapidly, which causes upward movement of the cantilever portion 6| and clockwise rotation. of. the ratchet wheel 32. .Due ,to a tooth arr nrra on thi ratchet wheelengagingthesnriace 66 of pawl 34 this clockwise movement or the ratchet wheel '32 'causes simdltaneousficlockwise move ment of the disc, 3 I *and damper 2 9, thusslowly moving the damperl toward open pas ion. when the damper is rotated to approximate' ly the predetermined maximum openpo'sition 'as determined by the adjustment of plate the pawl34 engages s'topQ-sv Upon slightly further rotation of the disc *31 the pawl 341s caused to ride clear of "theratchet wheel 32. Consequently theratc'het wheel 32 is now 'free 'to'rotate whi'ch permits "continued movement of 'the *bimetal element under the action eras heating means. This arrangement prevents any straining "of' the bime'ta'l "element. When the bimetal element warps tO'apoint "in-which:the contact blade is permitted to disengage blade {1i}; the ri ght hand portion of the "heater '64 is deenergizd. This *reducesjthe running temperature of "the thermostatic element 'and al's'o prolongs 'the life Crash r-e4. I

"When the room thermostat 1,8 "becomes "satishead the relay *8 is deenergized, "which stops the Stoker motor 5 and also :deen'ergizes the heater Ed. The thermostatic element and heater, due to the thermal inertia thereof, remain not for a period of time afterthe Stoker stops, and-conseguently the damper -29 remains open for a period "of time. This permits 'a supply of air "to the fire by natural draft, which serves to -supply air-tothe' fuel bed forburning ofi-thevolatile constituents of the green coalsnbriliedtoth fuel bedjustbeforethe sto-ker stopped. "*lh'is-delayin closing "of the 'damper 29 fOHQWiIlg stopping of the *stoker thus serves to reduce smoking. At this time the end-of pawl3-3 is disengaged "-from the s'top 4-2 and consequently thesurface '35 of this pawl'is-in engagement Witha-tddth-omthe ratchet wheel. '-When-the therinostatic element begins cooling, the cantilever portion 6-1 moves downwardly causing counterclockwise rotation o'f the ratchet wheel' 32pan'd due to the engagement of-pawl' 3 3 therewith, the disc ill rotates correspondingly for rotating the damper -=toward closed position. *When the 'damper ZB reaches the predetermined closed position the pawl 3-3 engages the stop-fl z, and thus further rotation of the ratchet Wheel 32 causes the pawlft'yto ride clear of the-ratchetwheell as shown for permitting free movement f this wheel; A 'a result :the thermostatic element is free to return to its normal cold position asshown, without any stress being placed:on=thiseelement or other parts of --the motion transmitting means During the cooling :movement of the thermostatic element the switch operating member 'lfi presse s contact blade 1%| "into engagement Withblade 10, further downward -movement of member 16 resulting "in flexing 'of both'blades asshown.

From-the above description it will-be apparent that the 10st motion transmitting means serves to permit 'freemovemento'f the thermostatio element after the damper is shifted to "running p0- s'ition, this "serving to prevent s'training of'the element. This same arrangement also provides for im'mediate'movement of -the'-damper one way or the other, with initial movement of'the ther mostatic element in one direction orthe other, irrespective of the actual temperature of the thermostatic element. This arrangement "provides foractuating the damper by change-in temperature of the thermostatic element. "This automatically con' pensates f-or-the i'efiect of am b'ient temperature andalso provides better control ve fthe opening and lclosing movements of the damper. It also be apparent that the anrangement above described provides for utilization ofa maximum ramountso'f 'heat upon initial movement of the damper, the heater then being partially deenerg-i-zed until movement of :the damper in the opposite direction is :d'esi-red.

arrangement conserves on eurrent :consumption and reduces the running temperature of the thermostatic element, thereby increasing the li'fe iof this element and of the heater. in addition, this arrangement increases the flexibility in timing of the device.

m'any variations may Joe made from the embodiments illus'trated withoutdeparting from the scope of the invention, it is desired "to be i lim'ite'cl only by the scope of the appended claims.

What-is claimed is:

1. In a control system for a stoher having fuel feeding means and air :feeding means, the combinatiomoL a controllerior startingand stopping the "fuel feeding means, adamper forvcontrolling the air xfeeding means, a thermostatic element having electric "heating means therefor, :a damper operating element, motion transmitting means between said thermostatic element and said damper operating element, said :motion transmitting means comprising a *firstrmember attached to the damper operating element anda second member cooperating with :the ifirst 'memher and :attached Ito the thermostatic ielement, means for causing said :second member *to move the'first'member upon initial imovementsof rthe second member in either direction @while permitting continuedmovementof'the. secondmember fin either direction after movement :of the first member in 'the corresponding direction is stopped, and means for energizing or :deenergizing said electric heating means to cause -movement of the damper to air retarding position whenthe fuel feedin means isout of operation and 'for'causingmovement of the damper to air feeding position when the fuel feeding means is in operation.

2*. In a=coritrolsystem-for a Stoker-having fuel feeding means 'and 'air feeding -means, thecombination of, a controller 'for starting and stopping the =rue1 feeding means, a-damper forcontrolling the air feeding means, a thermostatic element having electric heating =means therefor, a damper operating element,motlon transmitting means between said thermostatic element and said damper "operating element, said motion transmitting 'means comprising a first member attached to the "damper "operatingelement anda second member cooperating with the first -memher and attached to the thermostatic element, means for limiting movement of the damper in closing direction, adjustable limiting means for limiting movement of the damper in opening direction, means associated with said first and second'members and arranged to permit the second member to continue movement under the infiu'ehcefdf-said thermostatic element after move ment oi the first member is limited by one of said limiting means, while causing immediate movement "of "the first member with the second member upon initial movement -of the second member 'in'the opposite direction, and meansfor energizing or deenergizing said electric heating meansto cause "movementof the damper -to-air retarding position when-the fuel feedingmeans lsout of operation and for causing-movement of the damper-to "air-"Teeding-positiom when 1 the fuel feeding means *is in op'eration.

damper, said motion transmitting means ing means for causing movement of the damper 3. In a control system for a stoker having fuel feeding means and air feeding means, the combination of, a controller for starting and stopping the fuel feeding means, a damper for controlling the air feeding means, stop means for limiting movement of the damper in closing direction, a thermostatic element, means for causing said thermostatic element to rise in temperature when the fuel feeding means is placed into operation and to fall in temperature when the fuel feeding means is placed out of operation, and self-adjusting motion transmitting means between the thermostatic element and damper, said motion transmitting means being con structed and arranged to cause movement of the damper away from said stop means toward air feeding position upon initial rise in temperature of the thermostatic element and irrespective of its actual temperature.

4. In a control system for a stoker having fuel feeding means and air feeding means, the combination of, a controller for starting and stopping the fuel feeding means, a damper for controlling the air feeding means, stop means for limiting the movement of the damper in opening direction, a thermostatic element, means for causing said thermostatic element to rise in temperature when the fuel feeding means is placed into operation and to fall in temperature when the fuel feeding means is placed out of operation, and self-adjusting motion transmitting means between the thermostatic element and damper, said motion transmitting means being constructed and arranged to cause movement of the damper away from said stop means toward air retarding position upon initial fall in temperature of the thermostatic element and irrespective of its actual temperature.

5. In a control system for a stoker having fuel feeding means and airfeeding means, the combination of, a controller for starting and stopping the fuel feeding means, a damper for controlling the air feeding means, stop means providing a limited range of movement for the damper, a thermostatic element arranged to change in temperature upon starting and stopping of the stoker, and self-adjusting mechanical motion transmitting means for transmitting motive force from the thermostatic element to the includfrom said stop means upon initial reversal in temperature of the thermostatic element in one direction and irrespective of the actual temperature of said thermostatic element.

6. In a control system for a stoker having fuel feeding means and air feeding means, the combination of, a controller for starting and stopping the fuel feeding means, a damper for controlling the air feeding means, stop means for limiting movement of the damper in both directions, a thermostatic element arranged to change in temperature upon starting and stopping of the stoker, and means including self-adjusting mo tion transmitting means between the thermostatic element and damper for causing movement of said damper from either limit of its range of movement upon an initial reversal in temperature of said thermostatic element and irrespective of the actual temperature thereof.

7. In a control system for a stoker having fuel feeding means and air feeding means, the combination of, a controller for starting and stop ping the fuel feeding means, a damper for controlling the air feeding means, stop means for limiting movement of the damper, a thermostatic element having electric heating means therefor, said electric heating means being controlled with the stoker and changing in temperature when the stoker is stopped or started, and means including self-adjusting motion transmitting means between the thermostatic element and damper for causing movement of the damper away from said stop means upon initial reversal in temperature of the thermostatic element and irrespective of the actual temperature thereof.

8. In a control system for a stoker having fuel feeding means and air feeding means, the combination of, a controller for starting and stopping the fuel feeding means, a damper for controlling the air feeding means, a thermostatic element having electric heating means therefor, said electric heating means being controlled with the stoker and changing in temperature when the stoker is stopped or started, adjustable stop means for limiting movement of the damper in air feed increasing direction, and motion transmitting means between said thermostatic element and said damper, said motion transmitting means including means for permitting continued movement of the thermostatic element after movement of the damper is stopped by said adjustable stop means, and for causing movement of the damper in the opposite direction .upon initial movement of the thermostatic element in the opposite direction and irrespective of the temperature of said thermostatic element.

9. In a control system for a stoker having fuel feeding means and air feeding means, the combination of, a controller for starting and stopping the fuel feeding means, a damper for controlling the air feeding means, a, thermostatic element having electric heating means therefor, said electric heating means being controlled with the stoker and changing in temperature when the stoker is stopped or started, adjustable stop means for limiting movement of the damper in air feed increasing direction, and motion transmitting means between said thermostatic element and said damper, said motion transmitting means including means for permitting continued movement of the thermostatic element after movement of the damper is stopped by said adjustable stop means.

10. In a control system for a stoker having fuel feeding means and air feeding means, the combination of, a controller for starting and stopping the fuel feeding means, a damper for controlling the air feeding means, a rotatable member attached to the damper for actuating the same, a wheel adjacent the rotatable member, a .pawl pivoted to the rotatable member and engaging the Wheel, a thermostatic element arranged to change in temperature when the fuel feeding means is stopped or started for rotating said wheel, and a stop engaged by the pawl when the damper is moved to a predetermined position for forcing said pawl away from said ,wheel for permitting continued movement of the thermostatic element while the damper remains stationary.

11. In a control system for a stoker having fuel feeding means and air feeding means, the combination of, a controller for starting and stopping the fuel feeding means, a damper for controlling the air feeding means, a rotatable member attached to the damper for actuating the same, a wheel adjacent the rotatable member, a pair of pawls pivoted to the rotatable member and engaging the wheel, said pawls being arranged to drive the rotatable member in opposite directions, a first stop engaged by one of said pawls when the damper is moved to a first predetermined position for forcing said one pawl away from said wheel and a second stop engaged by the other of said pawls when the damper is moved to a second predetermined position for forcing said other pawl away from said wheel.

12. In combination, a rotatable device to be positioned, a. rotatable drive member for driving said device, a wheel adjacent said drive member, a pair of pawls pivoted to the rotatable drive member and engaging the wheel, said pawls being arranged to drive the rotatable member in opposite directions, a thermostatic element for rotating said wheel, a first stop engaged by one of the pawls when the rotatable device reaches a first predetermined position for forcing said one pawl away from the wheel and a second stop engaged by the other of said pawls when the rotatable drive member reaches another predetermined position for forcing said other pawl away from the wheel.

13. In combination, a wheel, a thermostatic element for rotating said wheel, a rotatable mem ber adjacent the wheel, a pair of pawls pivoted to the rotatable member and engaging the wheel, said pawls being arranged to drive the rotatable member in opposite directions, a first stop engaged by one of the pawls when the rotatable member reaches a first predetermined position for forcing one pawl away from the wheel, and a second stop engaged by the other of said pawls when the rotatable drive member reaches another predetermined position for forcing said other pawl away from the wheel.

14. In combination, a wheel, means including a thermostatic element for rotating the wheel in one direction on rise in temperature and for rotating the wheel in the opposite direction on fall in temperature, a rotatable member adjacent said 10 wheel, a pawl pivoted to the rotatable member and engaging the wheel, a stop engaged by the pawl when the rotatable member reaches a predetermined position for forcing the pawl away from the wheel thereby permitting continued 'movement of the thermostatic element while the rotatable member remains stationary, and means between the wheel and rotatable member for driving the rotatable member in the reverse direction upon rotation of the wheel in the reverse direction.

15. In combination, a wheel, means including a thermostatic element for rotating the wheel in one direction on rise in temperature and for rotating the wheel in the opposite direction on fall in temperature, a rotatable member adjacent said wheel, a pawl pivoted to the rotatable member and engaging the wheel, a stop engaged by the pawl when the rotatable member reaches a predetermined position for forcing the pawl away from the wheel thereby permitting continued movement of the thermostatic element while the rotatable member remains stationary, and means for driving the rotatable member in the reverse direction upon rotation of the wheel in the reverse direction.

16. In combination, a wheel, means including a thermostatic element for rotating the wheel in one direction on rise in temperature and for ro- ,tating the wheel in the opposite direction on fall in temperature, a rotatable member adjacent said wheel, a pawl pivoted to the rotatable member and engaging the wheel, and a stop engaged by the pawl when the rotatable member reaches a predetermined position for forcing the pawl away from the Wheel thereby permitting continued movement of the thermostatic element while the rotatable member remains stationary.

HOMER E. MALONE. CLIFFORD HOTCHKISS. 

